Update kubeadm-config.md (#27201)

add link to https://kubernetes.io/docs/setup/production-environment/tools/kubeadm/kubelet-integration/

Author: rdxmb

content/en/docs/reference/setup-tools/kubeadm/kubeadm-config.md

@@ -20,6 +20,13 @@ For more information navigate to
 [Using kubeadm init with a configuration file](/docs/reference/setup-tools/kubeadm/kubeadm-init/#config-file)
 or [Using kubeadm join with a configuration file](/docs/reference/setup-tools/kubeadm/kubeadm-join/#config-file).
 
+You can also configure several kubelet-configuration options with `kubeadm init`. These options will be the same on any node in your cluster. 
+See [Configuring each kubelet in your cluster using kubeadm](/docs/setup/production-environment/tools/kubeadm/kubelet-integration/) for details.
+
+In Kubernetes v1.13.0 and later to list/pull kube-dns images instead of the CoreDNS image
+the `--config` method described [here](/docs/reference/setup-tools/kubeadm/kubeadm-init-phase/#cmd-phase-addon)
+has to be used.
+
 <!-- body -->
 ## kubeadm config view {#cmd-config-view}